Retrospective analysis studies 'silent' strokes

Published online 14 June 2011

Mohammed Yahia

Children with sickle cell disease are often susceptible to silent brain infarcts, or 'silent' strokes, which can lead to neurocognitive impairments. Blood transfusions can prevent brain infarcts in these children, but how transfusions work to prevent infarcts is still unknown.

A team of researchers from the Medical University of South Carolina, United States, and the American University of Beirut (AUB), Lebanon, retrospectively analyzed data gathered from the STOP II trial, which took place between 2000 and 2004. They looked at magnetic resonance imaging (MRI) data to optimize stroke prevention in sickle cell anaemia patients and study the effect that ceasing transfusions has on the formation of silent infarcts. They published their findings in the journal Blood.

A total of 79 sickle cell patients found to at high risk for stroke by transcranial Doppler ultrasonography, a way to view the flow of blood around the brain, were divided into two groups. The first group continued transfusion treatment and the other group no longer received transfusions. 27.5% of the group that stopped transfusions developed new silent infarcts, compared to only 8.1% of the children who continued receiving transfusions. At the end, the number of brain lesions in the cohort that stopped transfusions rose from 27 to 45, while it stayed more or less the same in the other group.

"This demonstrates a very clear protective effect of transfusions," said Miguel Abboud, a pediatrician at AUB and the principle investigator in the research. "It remains to be seen whether transfusions are effective in patients with silent infarcts but normal transcranial Doppler."

Based on their data, researchers contend that blood transfusions are largely effective in preventing silent infarcts in children. They do warn that chronic transfusion therapy has its share of complications, such as the risk of viral infection or toxic iron build, but these can be minimized through careful screening. They suggest that further studies are needed to determine patients at particularly high risk of developing silent infarcts and to develop effective preventive strategies for them.